I personally think it's used to just label someone who has a personality that isn't liked by the majority of people. Although i can see how people find it uncomfortable to be around someone talking about strange things, i think people in society should be more accepting.

I think mental illness is a normal healthy reaction to social circumstances.

I also think that the 'chemical' idea behind mental illness isn't too valid. I think it's an effect of the way your treated. The chemicals dictate your perosnality, but only we release the chemicals. For example if you fail a test, you will have less seretonin. At that point you could be diagnosed with depression.

Let's say alot of bad things happened and you had low levels of seretonin, are you depressed, or reacting to social situations in a normal way?

Also people who are psychotic, i think have too much of the chemical dopamine, but in almost all cases social withdrawl takes place first. Eventually the perosn starts to hallucinate, and create a world of their own. Perhaps this is a healthy reaction of your mind, to keep you entertained when your very lonely.